Dialog box that pop up in a webpage will enhance interactivity of the webpage. A dialog normally carries a message or question that required some form of action from the user, either clicking a button or pressing a key on the keyboard .The syntax is very simple, you just need to use the alert method. The structure is as follows:
<HEAD>
<SCRIPT LANGUAGE="JavaScript">
windows.alert("Welcome to JavaScript Tutorial");
</SCRIPT>
<HEAD>
Adding this Script will allow the user too see a popup dialog box that displays the message "welcome to JavaScript Tutorial" as you have seen when you come to this visit this page, as I have put this line in this webpage. Refresh this page will let you see the dialog box again as shown in the diagram below:

You can customized the format of the output using a backslash \ and "n". Lets change the line windows.alert("Welcome to JavaScript Tutorial") to
window.alert"welcome to\nJavaScript\nTutorial"). The output will be displayed in three lines now, as shown below:

If you put the two scripts together, you will see two dialog boxes appear successively, after you click the first one, the second one will appear.
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